UMA doesn't work when I'm on 3G

I've a blackberry bold 9700 os 5.0.0.862. I just got talkspot plan. The city I'm living in we just got 3G yesterday,so whenever I'm on 3G my UMA doesn't work but as soon as I switched it to 2G UMA comes back on. Was on the phone with rogers talkspot supports for over 2 Hours, and he suggested me to reinstall the os and i did but still the same. Any idea?